Automatic fire-alarm system.



No. 802,554. PATENTED OCT. 24, 1905. G. B. BOWELL.

AUTOMATIC FIRE ALARM SYSTEM.

APPLICATION FILED DBO. 31. 1903.

2 SHEETS-SHEET 1.

No. 802,554. PATENTED OUT. 24, 1905. G. B. BOWELL.

AUTOMATIC FIRE ALARM SYSTEM.

APPLICATION FILED DEG,31.1905.

2 SHEETS-SHEET 2.

91M.) C I l/tOZ Whine/sow 90196 2.190408 ZZ thereafter to remain in contact.

PATENT un on.

GEORGE B. BOW' ELL, OF LONDON, ENGLAND, ASSIGNOR TO THE PEAR- SON FIRE ALARM LIMITED, OF LONDON, ENG-LAND.

AUTOMATIC FllHE-ALARM SYSTEM.

' Specification of Letters Patent.

Patented Oct. 24, 1905.

Application filed be 31, 1903. Serial No. 187,342.

.To a, whom it may concern:

Be it known that I, GEORGE BENNETT BowELL, a subject of the King of Great Britain and Ireland, residing at 6 Scarsdale Villas, Kensington, London, England, have invented certain new and useful Improvements in Automatic Fire-Alarm Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention for improvements in automatic fire-alarm systems relates to an alarm installation in a building which sends a firecall to a central station. when the local circuits are acted on by thermostats under the influence of heat and which also sends a different or trouble-call in case of a break in thewires connecting the thermostats within the building.

Figure 1 is a diagrammatic View of an apparatus embodying my invention. Fig. 2 is a similar view showing a modification.

The apparatus employed in the said installation comprises a pair of wires and a transmitter driven by clockwork and held by a catch controlled by an electromagnet. The transmitter with the code-message on its periphery is connected, together with the transmitters from other installations, into a main-line circuit and is provided with an auxiliary contact which renders the code inoperative after the first signal unless the thermostats have acted. Now according to this invention each installation is operated by current derived from the mainline circuit and is protected by open-circuit thermostats that are connectedacross the pair of wires within the building. The installation comprises a clockwork transmitter, with code break-wheel, escapement-wheel, and an additional contact-wheel, an electromagnet controlling the escapement, and two relays.

In the accompanying diagram, M M show the main-line circuit. The transmitter T comprises the transmitting-disk or breakwheel I), on which bears the brush a, the escapement c d and the contact-disk g and contact-brush It. The contact-disk g is arranged to come into contact with brush it after the first revolution of wheel I) and It will be understood that this mechanism is driven by a mainspring and regulated as to its speed by the escapement, and to prevent the escapement from moving normally a detent is provided, which is pulled back to free the escapement upon the energization of the mag net E and held back mechanically during the actual breaking between brush a and break wheel 7) by the cam 0 and lever 19. In series with these parts M a b T E, &c., is the relay R, and in shunt with. the relay R is the relay r; but this latter is connected, as shown in the diagram, through A and B, which. are the wires throughout the installa tion and across which are connected the thermostats contacts. The relay R operates a contact 3 and the relay r a contact 25. Contact t is connected, as shown, to short-circuit magnet E, and contact 3 is normally out of action, but can short-circuit brush a and break-wheel b after the first revolution of wheel b-that is, upon the establishment of contact between g and h.

The action of the apparatus is as follows: Normally a portion of the main line current by reason of the resistance of relay R is diverted through thermostat-wire B, relay 7, and thermostat-wire A. This keeps contact t closed, and magnet E is not energized. Should a lire occur, and thus by means of any thermostat H short-circuit wires A and B, then relay r will let go the contact if, and thus magnet E will be thrown into the main-line circuit and will attract the detent j and allow the clockwork to start. There will be no current through the circuit 9 h i s, since owing to the contact between wires A and B the current will pass this way, and the relay R will be unable to attract its armature, or if armature should have been previously in the near position it will be unable to retain it, because the diflerence of potential across relay R will have been lowered almost to nothing. Hence the break-wheel b will signal its code several times, and this is known in the central ofiice as a fire-call. Now, if, on the other hand, either or both wires A B become disconnected then the effect is as follows: Relay T will let go its armature, and this action insures the release ofthe clockwork by cutting magnet E into the mainline circuit; but since circuit oi wire A, relay 1', and wire B is cut out the current through relay R is very much. increased, and this in sures contact 8 becoming closed even if it were not closed before. Hence the break wheel I) is only allowed to signal during its first revolution, because it is afterward shortcircuited through 8 i h g, and such a signal that is, the code-number transmitted once onlyis known in the central oflice to mean that such and such an installation is out of order and must receive prompt attention.

In a modified method of working we may connect the contact of relay R to the junction of E and B instead of to the terminal M, as shown, and provide additional gaps in the cam 0. The action is then precisely the same, except that in the case of a break in the circuit of wires A and B the transmitter I) only makes one revolution, the second and subsequent signals being prevented by stopping the motion of the transmitter instead of by allowing it to rotate short-circuited. An apparatus illustrating such modification is illustrated at Fig. 2.

What I claim, and desire to secure by Letters Patent, is I 1. In a thermostatic fire-alarm system, the combination with a transmitter, a main circuit, a branch of the main circuit and an electromagnet, of a main relay arranged as a shunt to the branch circuit, a local relay in the branch circuit, open-circuit thermostats across the branch circuit as shunts to the relays, a switch normally short-circuiting the electromagnet and adapted to be operated by the local relay, a switch operated by the main relay and adapted to stop the action of the transmitter, and an open switch in the short circuit of the transmitter and adapted to be closed by the transmitter at the end of the first round.

2. In a thermostatic fire-alarm system, the combination with a transmitter, a main circuit, a branch of the main circuit and an electromagnet, of a main relay arranged as a shunt to the branch circuit, a local relay in the branch circuit, open-circuit thermostats across the branch circuit as shunts to the re lays, a switch normally shortcircuiting the electromagnet and adapted to be opened by the local relay, a switch operated by the main relay to short-circuit the transmitter, and an open switch in the short circuit of the transmitter adapted to be closed by the transmitter at the end of the first round.

In testimony whereof Ihave affixed my signature in presence of two witnesses.

GEORGE B. BOWELL.

I/Vitnesses:

H. D. JAMEsoN, A. N UTTING. 

